Evaluation, treatment, referrals for treatment of psoriasis and psoriasiform dermatoses. Treatment of patients with extensive psoriasis who have not been responsive to conventional ambulatory treatment and for whom methotrexate, etretinate, PUVA, cyclosporine A and other modalities are contemplated. Immunological and molecular studies of patients' cells are monitored throughout therapy. Pilot studies mapping gene(s) for psoriasis. Modes of treatment other than PUVA.